from io import BytesIO

from ufile import filemanager, config, httprequest
from const import PUBLIC_KEY, PRIVATE_KEY, UPLOAD_SUFFIX, DOWNLOAD_SUFFIX


def _download_file_save_to_bio(url, header):
    try:
        response = httprequest.requests.get(url, headers=header, stream=True)
    except httprequest.RequestException as e:
        return None, httprequest.ResponseInfo(None, e)
    if response.status_code in [200, 206]:
        bio = BytesIO()
        for block in response.iter_content(config.BLOCKSIZE):
            bio.write(block)
    else:
        return
    return bio


class BioFileManager(filemanager.FileManager):
    def download_bytes_file(self, bucket, key, isprivate=True, expires=None, content_range=None, header=None):
        """
        :param bucket: string类型, UFile空间名称
        :param key: string类型， 下载文件在空间中的名称
        :param isprivate: boolean类型，如果为私有空间则为True
        :param expires: integer类型，私有文件链接有效时间
        :param content_range: tuple类型，元素为两个整型
        :param header: dict类型，http 请求header，键值对类型分别为string，比如{'User-Agent': 'Google Chrome'}
        :return: ret: 如果http状态码为[200, 204, 206]之一则返回None，否则如果服务器返回json信息则返回dict类型，键值对类型分别为string, unicode string类型，否则返回空的dict
        :return:  ResponseInfo: 响应的具体信息，UCloud UFile 服务器返回信息或者网络链接异常
        """
        if header is None:
            header = dict()
        else:
            filemanager._check_dict(header)

        if expires is None:
            expires = config.get_default('expires')

        if 'User-Agent' not in header:
            header['User-Agent'] = config.get_default('user_agent')

        if isinstance(content_range, tuple) and len(content_range) == 2:
            header['Range'] = 'bytes=' + '-'.join(map(lambda x: str(x), content_range))

        if not isprivate:
            url = self.public_download_url(bucket, key)
        else:
            url = self.private_download_url(bucket, key, expires, header, True)

        return _download_file_save_to_bio(url, header)


client = BioFileManager(PUBLIC_KEY, PRIVATE_KEY, UPLOAD_SUFFIX, DOWNLOAD_SUFFIX)